Typically, during an initial alignment process (in which a set of speakers of an audio playback system is initially calibrated), pink noise (or another stimulus such as a sweep or pseudo-random noise sequence) is played through each speaker of the system and captured by a microphone. The pink noise (or other stimulus), as emitted from each speaker and captured by a “signature” microphone placed on a sidewall/ceiling/in-room, is typically stored for use during subsequent maintenance checks (quality checks). Such a subsequent maintenance check is conventionally performed in the playback system environment (which may be a movie theater) by exhibitor staff when no audience is present, using pink noise rendered through a predetermined sequence of the speakers (whose status is to be monitored) during the check. During the maintenance check, for each speaker sequenced in the playback environment, the microphone captures the pink noise emitted by the loudspeaker, and the maintenance system identifies any difference between the initially measured pink noise (emitted from the speaker and captured during the alignment process) and the pink noise measured during the maintenance check. This can be indicative of a change in the set of speakers that has occurred since the initial alignment, such as damage to an individual driver (e.g., woofer, mid-range, or tweeter) in one of the speakers, or a change in a speaker output spectrum (relative to an output spectrum determined in the initial alignment), or a change in polarity of the output of one of the speakers, relative to a polarity determined in the initial alignment (e.g., due to replacement of a speaker). The system can also use loudspeaker-room responses deconvolved from pink-noise measurements for analysis. Additional modifications include gating or windowing the time-response to analyze the direct sound of the loudspeaker.
However, there are several limitations and disadvantages of such a conventionally implemented maintenance check, including the following: (i) it is time-consuming to run pink noise individually and sequentially through a theater's loudspeakers, and to de-convolve each corresponding loudspeaker-room impulse response from each microphone (typically located on a wall of the theater), especially since a movie theater may have as many as 26 (or more) loudspeakers; and (ii) performing the maintenance check does not aid in promoting the theater's audiovisual system format directly to an audience in the theater.